<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: ZendPlatform.php 23775 2011-03-01 17:25:24Z ralph $
 */

/**
 * @see Zend_Cache_Backend_Interface
 */
require_once 'Zend/Cache/Backend.php';

/**
 * @see Zend_Cache_Backend_Interface
 */
require_once 'Zend/Cache/Backend/Interface.php';

/**
 * Impementation of Zend Cache Backend using the Zend Platform (Output Content Caching)
 *
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Cache_Backend_ZendPlatform extends Zend_Cache_Backend implements Zend_Cache_Backend_Interface {
	/**
	 * internal ZP prefix
	 */
	const TAGS_PREFIX = "internal_ZPtag:";
	
	/**
	 * Constructor
	 * Validate that the Zend Platform is loaded and licensed
	 *
	 * @param  array $options Associative array of options
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	public function __construct(array $options = array()) {
		if (! function_exists ( 'accelerator_license_info' )) {
			Zend_Cache::throwException ( 'The Zend Platform extension must be loaded for using this backend !' );
		}
		if (! function_exists ( 'accelerator_get_configuration' )) {
			$licenseInfo = accelerator_license_info ();
			Zend_Cache::throwException ( 'The Zend Platform extension is not loaded correctly: ' . $licenseInfo ['failure_reason'] );
		}
		$accConf = accelerator_get_configuration ();
		if (@! $accConf ['output_cache_licensed']) {
			Zend_Cache::throwException ( 'The Zend Platform extension does not have the proper license to use content caching features' );
		}
		if (@! $accConf ['output_cache_enabled']) {
			Zend_Cache::throwException ( 'The Zend Platform content caching feature must be enabled for using this backend, set the \'zend_accelerator.output_cache_enabled\' directive to On !' );
		}
		if (! is_writable ( $accConf ['output_cache_dir'] )) {
			Zend_Cache::throwException ( 'The cache copies directory \'' . ini_get ( 'zend_accelerator.output_cache_dir' ) . '\' must be writable !' );
		}
		parent::__construct ( $options );
	}
	
	/**
	 * Test if a cache is available for the given id and (if yes) return it (false else)
	 *
	 * @param  string  $id                     Cache id
	 * @param  boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
	 * @return string Cached data (or false)
	 */
	public function load($id, $doNotTestCacheValidity = false) {
		// doNotTestCacheValidity implemented by giving zero lifetime to the cache
		if ($doNotTestCacheValidity) {
			$lifetime = 0;
		} else {
			$lifetime = $this->_directives ['lifetime'];
		}
		$res = output_cache_get ( $id, $lifetime );
		if ($res) {
			return $res [0];
		} else {
			return false;
		}
	}
	
	/**
	 * Test if a cache is available or not (for the given id)
	 *
	 * @param  string $id Cache id
	 * @return mixed|false false (a cache is not available) or "last modified" timestamp (int) of the available cache record
	 */
	public function test($id) {
		$result = output_cache_get ( $id, $this->_directives ['lifetime'] );
		if ($result) {
			return $result [1];
		}
		return false;
	}
	
	/**
	 * Save some string datas into a cache record
	 *
	 * Note : $data is always "string" (serialization is done by the
	 * core not by the backend)
	 *
	 * @param  string $data             Data to cache
	 * @param  string $id               Cache id
	 * @param  array  $tags             Array of strings, the cache record will be tagged by each string entry
	 * @param  int    $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)
	 * @return boolean true if no problem
	 */
	public function save($data, $id, $tags = array(), $specificLifetime = false) {
		if (! ($specificLifetime === false)) {
			$this->_log ( "Zend_Cache_Backend_ZendPlatform::save() : non false specifc lifetime is unsuported for this backend" );
		}
		
		$lifetime = $this->_directives ['lifetime'];
		$result1 = output_cache_put ( $id, array ($data, time () ) );
		$result2 = (count ( $tags ) == 0);
		
		foreach ( $tags as $tag ) {
			$tagid = self::TAGS_PREFIX . $tag;
			$old_tags = output_cache_get ( $tagid, $lifetime );
			if ($old_tags === false) {
				$old_tags = array ();
			}
			$old_tags [$id] = $id;
			output_cache_remove_key ( $tagid );
			$result2 = output_cache_put ( $tagid, $old_tags );
		}
		
		return $result1 && $result2;
	}
	
	/**
	 * Remove a cache record
	 *
	 * @param  string $id Cache id
	 * @return boolean True if no problem
	 */
	public function remove($id) {
		return output_cache_remove_key ( $id );
	}
	
	/**
	 * Clean some cache records
	 *
	 * Available modes are :
	 * Zend_Cache::CLEANING_MODE_ALL (default)    => remove all cache entries ($tags is not used)
	 * Zend_Cache::CLEANING_MODE_OLD              => remove too old cache entries ($tags is not used)
	 * This mode is not supported in this backend
	 * Zend_Cache::CLEANING_MODE_MATCHING_TAG     => remove cache entries matching all given tags
	 * ($tags can be an array of strings or a single string)
	 * Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG => unsupported
	 * Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG => remove cache entries matching any given tags
	 * ($tags can be an array of strings or a single string)
	 *
	 * @param  string $mode Clean mode
	 * @param  array  $tags Array of tags
	 * @throws Zend_Cache_Exception
	 * @return boolean True if no problem
	 */
	public function clean($mode = Zend_Cache::CLEANING_MODE_ALL, $tags = array()) {
		switch ($mode) {
			case Zend_Cache::CLEANING_MODE_ALL :
			case Zend_Cache::CLEANING_MODE_OLD :
				$cache_dir = ini_get ( 'zend_accelerator.output_cache_dir' );
				if (! $cache_dir) {
					return false;
				}
				$cache_dir .= '/.php_cache_api/';
				return $this->_clean ( $cache_dir, $mode );
				break;
			case Zend_Cache::CLEANING_MODE_MATCHING_TAG :
				$idlist = null;
				foreach ( $tags as $tag ) {
					$next_idlist = output_cache_get ( self::TAGS_PREFIX . $tag, $this->_directives ['lifetime'] );
					if ($idlist) {
						$idlist = array_intersect_assoc ( $idlist, $next_idlist );
					} else {
						$idlist = $next_idlist;
					}
					if (count ( $idlist ) == 0) {
						// if ID list is already empty - we may skip checking other IDs
						$idlist = null;
						break;
					}
				}
				if ($idlist) {
					foreach ( $idlist as $id ) {
						output_cache_remove_key ( $id );
					}
				}
				return true;
				break;
			case Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG :
				$this->_log ( "Zend_Cache_Backend_ZendPlatform::clean() : CLEANING_MODE_NOT_MATCHING_TAG is not supported by the Zend Platform backend" );
				return false;
				break;
			case Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG :
				$idlist = null;
				foreach ( $tags as $tag ) {
					$next_idlist = output_cache_get ( self::TAGS_PREFIX . $tag, $this->_directives ['lifetime'] );
					if ($idlist) {
						$idlist = array_merge_recursive ( $idlist, $next_idlist );
					} else {
						$idlist = $next_idlist;
					}
					if (count ( $idlist ) == 0) {
						// if ID list is already empty - we may skip checking other IDs
						$idlist = null;
						break;
					}
				}
				if ($idlist) {
					foreach ( $idlist as $id ) {
						output_cache_remove_key ( $id );
					}
				}
				return true;
				break;
			default :
				Zend_Cache::throwException ( 'Invalid mode for clean() method' );
				break;
		}
	}
	
	/**
	 * Clean a directory and recursivly go over it's subdirectories
	 *
	 * Remove all the cached files that need to be cleaned (according to mode and files mtime)
	 *
	 * @param  string $dir  Path of directory ot clean
	 * @param  string $mode The same parameter as in Zend_Cache_Backend_ZendPlatform::clean()
	 * @return boolean True if ok
	 */
	private function _clean($dir, $mode) {
		$d = @dir ( $dir );
		if (! $d) {
			return false;
		}
		$result = true;
		while ( false !== ($file = $d->read ()) ) {
			if ($file == '.' || $file == '..') {
				continue;
			}
			$file = $d->path . $file;
			if (is_dir ( $file )) {
				$result = ($this->_clean ( $file . '/', $mode )) && ($result);
			} else {
				if ($mode == Zend_Cache::CLEANING_MODE_ALL) {
					$result = ($this->_remove ( $file )) && ($result);
				} else if ($mode == Zend_Cache::CLEANING_MODE_OLD) {
					// Files older than lifetime get deleted from cache
					if ($this->_directives ['lifetime'] !== null) {
						if ((time () - @filemtime ( $file )) > $this->_directives ['lifetime']) {
							$result = ($this->_remove ( $file )) && ($result);
						}
					}
				}
			}
		}
		$d->close ();
		return $result;
	}
	
	/**
	 * Remove a file
	 *
	 * If we can't remove the file (because of locks or any problem), we will touch
	 * the file to invalidate it
	 *
	 * @param  string $file Complete file path
	 * @return boolean True if ok
	 */
	private function _remove($file) {
		if (! @unlink ( $file )) {
			# If we can't remove the file (because of locks or any problem), we will touch
			# the file to invalidate it
			$this->_log ( "Zend_Cache_Backend_ZendPlatform::_remove() : we can't remove $file => we are going to try to invalidate it" );
			if ($this->_directives ['lifetime'] === null) {
				return false;
			}
			if (! file_exists ( $file )) {
				return false;
			}
			return @touch ( $file, time () - 2 * abs ( $this->_directives ['lifetime'] ) );
		}
		return true;
	}

}
